From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B3702C169C4 for ; Wed, 6 Feb 2019 15:21:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B6F81217F9 for ; Wed, 6 Feb 2019 15:21:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alien8.de header.i=@alien8.de header.b="bOeAn9H1" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729804AbfBFPVy (ORCPT ); Wed, 6 Feb 2019 10:21:54 -0500 Received: from mail.skyhub.de ([5.9.137.197]:59340 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727638AbfBFPVx (ORCPT ); Wed, 6 Feb 2019 10:21:53 -0500 Received: from zn.tnic (p200300EC2BCEF1005C27BB339FB20F69.dip0.t-ipconnect.de [IPv6:2003:ec:2bce:f100:5c27:bb33:9fb2:f69]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id 90B9D1EC0253; Wed, 6 Feb 2019 16:21:52 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1549466512; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:in-reply-to:in-reply-to: references:references; bh=r7L2QRjbby7JI5M+tVwgkVMWvJYnfojKDjotPL68V7g=; b=bOeAn9H1j1wkInEudzs/owyFBmiNZ8coCdK+ILIXeugoMvF5XGuGcWgcSTGj7FfcjgximQ RvILHz9tj5iFHRi1L24dpg+vlpayUcCBV2O0eEDfc13WWwIpDKg5JlROCGvw68UuVx+YUk Ty3lqZahPOD0kSz28MA2cqv7rfHYlGQ= Date: Wed, 6 Feb 2019 16:21:41 +0100 From: Borislav Petkov To: "Kirill A. Shutemov" Cc: tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, dave.hansen@linux.intel.com, x86@kernel.org, linux-kernel@vger.kernel.org, Kyle D Pelton , Wei Huang Subject: Re: [PATCH] x86/boot/compressed/64: Do not corrupt EDX on EFER.LME=1 setting Message-ID: <20190206152141.GF7314@zn.tnic> References: <20190206115253.1907-1-kirill.shutemov@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20190206115253.1907-1-kirill.shutemov@linux.intel.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Feb 06, 2019 at 02:52:53PM +0300, Kirill A. Shutemov wrote: > RDMSR in the trampoline code overrides EDX, but we use the register to > indicate if 5-level paging has to enabled. It leads to failure to boot > on a 5-level paging machine. > > Preserve EDX on the stack while we are dealing with EFER. Comment says: * Non zero RDX on return means we need to enable 5-level paging. Is that per-chance refering to struct paging_config which paging_prepare() returns and on that return rdx contains paging_config.l5_required which is 1 when 5 level is to be enabled? If so, is that written somewhere explicitly? Because it is not immediately clear at least to me why that RDX is live... Thx. -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.